Hitherto, as a hydrogen-generating agent for generating hydrogen gas by the supply of water, known is an agent made mainly of a metal such as iron or aluminum, or an agent made mainly of a metal hydride compound such as magnesium hydride or calcium hydride (see, for example, Patent Document 1).
Patent Document 2 also discloses a hydrogen-generating agent wherein a metal hydride is enveloped in a solid-form water-soluble compound such as a water-soluble resin in order to control the rate of reaction between the metal hydride and water appropriately.
In the meantime, Patent Document 3 discloses a hydrogen-generating device in which in each of the above-mentioned holding spaces a hydrogen-generating agent is held at a filling rate making it difficult to cause a reaction liquid to enter the space by the swelling of the hydrogen-generating agent when the reaction is substantially ended. It is stated about this hydrogen-generating device that as the reaction approaches the end thereof, the entry of the reaction liquid into one of the holding spaces is made difficult by the swelling of the hydrogen-generating agent, so that the reaction liquid is supplied through a supplying path to the adjacent holding space.